This invention relates to a liquid pump dispenser having a minimum of constituent parts and including a stationary spout, a stationary piston, container venting and pump priming features, and an inlet/discharge valve housing. More particularly, such dispenser is of the throttle pump variety having a positive leakproof vent control.
Known is a liquid pump dispenser disclosed in U.S. Pat. No. 4,402,432 having a pump priming feature and a positive container vent control for a pump of the pressure built-up variety having a reciprocable plunger defining a variable volume pump chamber with a fixed piston, and requiring a plunger head slidable relative to the plunger for controlling the discharge in response to accumulation of pressure within the pump chamber. The discharge passage reciprocates with the plunger head.
Also known is a pump dispenser from U.S. Pat. No. 4,218,198 which has a stationary spout and a fixed pump cylinder for the reception of a reciprocating piston. A circular discharge flap valve is located between the pump chamber and the discharge passage, and a separate vent seal defining a passive vent is provided.
It is desirable to provide an improved pump dispenser of the throttle variety having a minimum number of parts for economy and simplicity yet avoiding the performance and operational drawbacks of the known pump structures.